1. Field of the Invention
The present invention relates to the preparation and use of zona pellucida (ZP) antigens and monoclonal antibodies for contraception or sterilization in individuals. The present invention also relates to immunological contraception. More specifically, the present invention relates to immunological contraception utilizing zona pellucida antigens produced by recombinant DNA technology to actively immunize an individual against pregnancy, or monoclonal antibodies prepared against the zona pellucida antigens to passively immunize the individual. In addition, the present invention relates to the use of anti-idiotypic monoclonal antibodies which would mimic ZP antigens to actively immunize an individual against pregnancy.
This invention also relates to monoclonal anti-zona pellucida antibody, to novel hybridoma cells which express such antibody, and to a method for producing such hybrid cells and anti-zona pellucida antibody.
2. Brief Description of the Background Art
The zona pellucida is the complex extracellular glycoprotein matrix which surrounds the mammalian oocyte. This matrix is formed during the early stages of oocyte growth and follicular cell differentiation and serves to protect the oocyte and embryo until implantation in the uterine wall (Austin, et al., Reproduction in Mammals: Germ Cells and Fertilization, Cambridge Univ. Press, Cambridge, England (1982)). In addition, the zona pellucida plays an important role in the fertilization process since the sperm must first adhere to and penetrate the zona pellucida. After binding to the zona pellucida of an oocyte, the sperm must penetrate the zona pellucida. Sperm penetration of the zona pellucida is probably mediated by the limited hydrolysis of zona pellucida components by sperm enzymes such as acrosin (McRorie et al., Ann. Rev. Biochem. 43: 777 (1974); Dunbar et al., Biol. Reprod. 32:619 (1985), and Stambaugh, Gam. Res. 1:65, 1978). The zona pellucida remains intact after fertilization, to ensure proper embryonic development and perhaps to prevent embryo fusion in the oviduct (Mintz, Science 138:594, 1962).
Finally, the zona pellucida plays a role in the block to polyspermy. In some mammalian species, fertilization alters sperm binding to the zona and its resistance to proteolytic digestion (Austin and Braden, J. Exp. Biol. 33:358, 1956).
There are major biological, morphological, physiological and immunochemical variations in properties among the zona pellucida of rodents as compared with the zona pellucida of other species including sub-human primates and humans. See reviews by Dunbar, In Mechanism and Control of Fertilization (J. Hartmann, ed.), Academic Press, New York, pp. 139 (1983); Dunbar, In International Congress on Reproductive Immunology (Wegmann and Gill III, eds.), Oxford Univ. Press, London, pp. 505 (1983) and Dunbar et al., In: Modern Cell Biology 3, (Satir, ed.) Alan R. Liss, New York, pp. 77 (1984). Although mammalian zona pellucida is composed of a limited number of major glycoproteins (Bleil et al., Dev. Biol. 76:185 (1980); Dunbar et al., Biol. Reprod. 24:1111 (1981); Timmons and Dunbar, Biol. Reprod. (1987)), the structural and functional relationships of zona pellucida proteins of different species vary.
Attempts to develop an effective and economical method of immunocontraception have been hindered by the lack of sufficient material to produce quantities of antigen or antibodies needed to produce a vaccine which would either inhibit fertilization of the oocyte by the sperm, prevent implantation of a fertilized egg, or prevent the development of the ovaries thereby making the animal permanently sterile. Early attempts to develop immunocontraceptive methods have not been very successful. These attempts have included the use of naturally occurring circulating peptide hormones such as human chorionic gonadotrophin (hCG) and follicle stimulating hormone (Griffin, In Immunological Approaches to Contraception and Promotion of Fertility, G. P. Talwan, Ed., Plenum Press, New York (1986)). Immunocontraception utilizing antibodies against normally "circulating" antigens poses the problem that immune complexes might form which would bring about undesirable tissue damage. Furthermore, immunization with "circulating" antigens has not proven totally effective in inhibiting fertility.
Immunologically based methods of contraception are preferable to other commercially available methods such as surgical sterilization or birth control pills (for humans and pets) in which there is a continuous expense for medication which must be used and purchased on a regular basis and are only indicated for use on a temporary basis. Thus, a considerable need exists for antigen preparations that can induce transient or permanent contraception in an individual and which can be provided in a safe, reliable and cost effective manner.